The word(s) "back" appears 161 time(s) in 150 verse(s) in Quran in Mohsin Khan translation.

(121) And he made it [i.e. La ilaha illallah (none has the right to be worshipped but Allah Alone)] a Word lasting among his offspring, (True Monotheism), that they may turn back (i.e. to repent to Allah or receive admonition).

(122) "Then bring back our forefathers, if you speak the truth!"

(123) And when Our Clear Verses are recited to them, their argument is no other than that they say: "Bring back our (dead) fathers, if you are truthful!"

(124) Verily, those who have turned back (have apostatised) as disbelievers after the guidance has been manifested to them - Shaitan (Satan) has beautified for them (their false hopes), and (Allah) prolonged their term (age).

(125) Then how (will it be) when the angels will take their souls at death, smiting their faces and their backs?

(126) No blame or sin is there upon the blind, nor is there blame or sin upon the lame, nor is there blame or sin upon the sick (that they go not for fighting). And whosoever obeys Allah and His Messenger (Muhammad صلى الله عليه وسلم), He will admit him to Gardens beneath which rivers flow (Paradise); and whosoever turns back, He will punish him with a painful torment.

(127) And if those who disbelieve fight against you, they certainly would have turned their backs; then they would have found neither a Wali (protector, guardian) nor a helper.

(128) O you who believe! Avoid much suspicion; indeed some suspicions are sins. And spy not, neither backbite one another. Would one of you like to eat the flesh of his dead brother? You would hate it (so hate backbiting) . And fear Allah. Verily, Allah is the One Who forgives and accepts repentance, Most Merciful.

(129) Their multitude will be put to flight, and they will show their backs.

(130) No Laghw (dirty, false, evil vain talk) will they hear therein, nor any sinful speech (like backbiting).